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Thread: Bad muriatic acid? Added gallon still high ph.

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    Bad muriatic acid? Added gallon still high ph.

    I added a gallon of Muriatic acid and my pH is still reading 8.2 which means it is presumably higher.

    The pool calculator only goes to 8.6. Does that mean that is as high as my pH could be? If so according to the calculator I shouldn't have had to add that much to go from 8.6 to 7.5.

    My muriatic acid was a couple years old and I've read that it doesn't "expire" so what gives?

    BTW my FC is 5 and my CYA is ~40.
    10,000 gallon
    Viking Freeform Fiberglass Inground Pool. FNS Plus DE Filter Pentair Challenger .75hp pump

    NC KANSAS44

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    Join Date
    Mar 2016
    Location
    Gilbert AZ
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    45

    Re: Bad muriatic acid? Added gallon still high ph.

    I've had really weak batches of Acid...maybe your PH was sky high + weak acid?

    Just add more let it mix and retest....repeat until you are good.

    *EDIT
    Also make sure whatever your using to measure the PH is accurate...if using drops make sure they aren't expired.
    11,507 Gallons | In Ground Pebble Tec | QC XHP In Ground Cleaning System | System 3 MM Sta-Rite Filter | Pentair VS-T 3050 Pump | Pentair Ultra Temp 120 H/C | QuickPure 3 Ozone | K2006 Test Kit

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    Join Date
    Mar 2017
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    Villa Park/California
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    19

    Re: Bad muriatic acid? Added gallon still high ph.

    Do you know what strength it is? I purchased several bottles from Home Depot before realizing it was only 14.5%. A gallon of that stuff barely dented my pH and TA when it was high. Now I buy the HASA stuff from a local pool store. I think it is 31.5% and a much better value.
    18,000ish gallon outdoor gunite pool & small spa (built in 1970s, re-plastered at least once)
    3HP Pentair Inteleflo VS Pump-011018; Waterway Crystal Water/Aqua Clean Cartridge Filter 570-425; Rheem 267A Gas Heater; Taylor K-2006 for pool chemistry testing

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    Richard320's Avatar
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    Jan 2010
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    San Dimas, CA (LA County)
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    Re: Bad muriatic acid? Added gallon still high ph.

    Your pH could be much higher than the tester is capable of reading. And pH is logarithmic. The jump from 8.0 to 9.0 pH is ten times larger than the jump from 7.0 to 8.0. Just keep dosing with Now as 8.2 and eventually you'll get a shift. Once you're below the limit of the testblock, things should behave.

    A good doublecheck is to compare your readings with what Effects of Adding Chemicals (bottom of poolmath) says about TA reduction for a given amount of acid. The pH calculation will be so far off you should try to not even read it but the TA drop is usually right on.

    And also, if that acid is marked anywhere as "low-fuming" or "Safe" it is watered down.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
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    Re: Bad muriatic acid? Added gallon still high ph.

    What's your TA?
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    Re: Bad muriatic acid? Added gallon still high ph.

    It was the full strength muriatic acid I can guarantee that. I haven't measured TA mainly because I know the well water I filled my pool with has high TA and I didn't want to waste the drops.

    My assumption was that continuing to drop pH would naturally drop TA. Sounds like a trip to Lowes for a new gallon or two of muriatic acid is likely the answer:

    Also I've used two different test kits to test so the reagent isn't bad. One is brand new.

  7. Back To Top    #7

    Re: Bad muriatic acid? Added gallon still high ph.

    You need to enter the TA into the calculator for the calculator to calculate the correct amount of acid to use to lower the ph.

    If you’re waiting 24 hours to retest, the pH might have gone back up due to the high TA.

    When adding acid, make sure the pump is on and brush the pool after adding the acid.

    Retest after about 30 minutes after thoroughly brushing the pool.

    Also, until the TA is correct, you should be lowering the pH to 7.2 each time.
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    Re: Bad muriatic acid? Added gallon still high ph.

    TAis 220. High as I suspected. Added acid to reduce pH to7.2. I'll test again later. I didn't have time to brush but will do that if I have to add more.Thanks.

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